Hi! I hope Lev will work well for Milo. Yes, with Lev and Lantus we try to test, feed, and shoot all within about 10 or 15 minutes. No need to wait to inject. Also, keep in mind that Lev onsets much later than Lantus or Prozinc. For Rusty onset usually begins at +4 or later. The late onset is good to know about, because if you have a low bg number at PS, Milo's bg will probably be rising until onset kicks in.
ECID, so keep good records. And don't forget that it takes about a week to build the "shed" and therefore not all of the insulin is available to work on the bg because it is going into the shed. (and every time you adjust the dose, it takes a couple of days for the shed to adjust to the new dose).
Best of luck!
Ella & Rusty